pkg/logutil: change "NewRaftLogger" function signature

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

pkg/logutil/zap_raft.go

@@ -15,6 +15,8 @@
 package logutil
 
 import (
+	"errors"
+
 	"github.com/coreos/etcd/raft"
 
 	"go.uber.org/zap"
@@ -22,7 +24,10 @@ import (
 )
 
 // NewRaftLogger converts "*zap.Logger" to "raft.Logger".
-func NewRaftLogger(lcfg zap.Config) (raft.Logger, error) {
+func NewRaftLogger(lcfg *zap.Config) (raft.Logger, error) {
+	if lcfg == nil {
+		return nil, errors.New("nil zap.Config")
+	}
 	lg, err := lcfg.Build(zap.AddCallerSkip(1)) // to annotate caller outside of "logutil"
 	if err != nil {
 		return nil, err

pkg/logutil/zap_raft_test.go

@@ -32,7 +32,7 @@ func TestNewRaftLogger(t *testing.T) {
 	logPath := filepath.Join(os.TempDir(), fmt.Sprintf("test-log-%d", time.Now().UnixNano()))
 	defer os.RemoveAll(logPath)
 
-	lcfg := zap.Config{
+	lcfg := &zap.Config{
 		Level:       zap.NewAtomicLevelAt(zap.DebugLevel),
 		Development: false,
 		Sampling: &zap.SamplingConfig{